Experts are predicting the worst coral bleaching in two decades could occur in the coming six to 12 months. It is another side effect of global warming.

Coral bleaching happens when coral eject their “zooxanthellae”. It is an alga like protozoan which live in the tissues of coral. The ejection occurs when the sea water becomes warmer or more acidic.

Healthy corals and these unicellular organisms share a symbiotic relationship with the former dependent on the latter for both the pigmentation it provides and its photosynthetic abilities. Without zooxanthellae, the corals do not die but become highly susceptible to disease. Corals also become unattractive to fish.

The Coral reefs are important for other marine creatures like smaller fish since they serve as sources of food and refuge. Corals also maintain the ocean diversity.

Researchers feel that coral bleaching will be more widespread in the coming times because of global warming and the sea water becoming more acidic.

Mark Eakin, head of National Oceanic and Atmospheric Administration’s Coral Reef Watch program said, “As the ocean becomes more acidified, the bleaching threshold for corals drops, more carbon dioxide makes corals more sensitive to thermal stress. Not only are we seeing more thermal stress but we’re making them more sensitive at the same time.”

El Nino, the periodic warming phase in the Pacific which occurs in two to seven years also precipitates massive coral bleaching. El Nino phenomenon can last from a couple of months to a year and brings a number of changes in the atmosphere as well as climate. As the ocean temperatures peak, El Nino is expected to trigger a domino effect upon coral bleaching phenomenon across the oceans.

The phenomenon of coral bleaching is expected all over the Pacific Islands and the shores of Australia. The most affected will be Florida, Hawaii, Guam, the Marianas Islands, Kiribati and Tuvalu.

The last bleaching event had occurred in 1998 and was caused by El Nino in concurrence with global warming.